TOPSIS-based optimization of machining, energy, and environmental performance in electro discharge turning of Hastelloy-X with synchronized tool feed–rotation

Abstract This study investigates the machining, energy, and environmental performance of Hastelloy-X in electro discharge turning (EDT) using a synchronized tool feed–rotation configuration. A full factorial design comprising 27 experiments was conducted by varying tool rotational speed, workpiece rotational speed, and peak current. Material removal rate (MRR), tool wear rate (TWR), relative tool wear (RTW), specific energy consumption (SEC), and electricity-related carbon emissions (CE) were evaluated. The non-rotating tool condition generally provided favorable MRR, TWR, RTW, and SEC performance, whereas higher tool rotational speed improved CE-related performance. Increasing workpiece rotational speed improved MRR, SEC, and CE but adversely affected tool wear, while higher peak current improved MRR and CE but increased TWR and RTW; the best average SEC was obtained at 25 A. TOPSIS optimization, based on maximizing MRR and minimizing TWR, SEC, and CE. The discrete TOPSIS analysis identified Experiment 21 ( n = 0 rpm, v = 1 rpm, and I p =37.5 A) as the best experimentally demonstrated condition. A complementary quadratic response-surface analysis predicted a continuous solution at n = 0 rpm, v = 2.363 rpm, and I p =30.4091 A, with a predicted C i * of 0.7717 and a desirability of 0.9578. Confirmation experiments supported the predictive performance of the proposed optimization approach.